1. Technical Field of the Invention
The present invention relates to a belt conveyor comprising a drum, which is rotatably mounted on a vertical center shaft, and an endless conveyor belt, which along part of its length follows a helical path through a plurality of turns around the drum and in contact with the outside of the drum.
2. Prior Art
Belt conveyors of this type are used in, e.g., freezing plants. The advancing of the conveyor belt is carried out with the aid of the drum, with the aid of means supporting the lowermost turn of the belt, with the aid of driving rollers outside the drum, or with the aid of a combination of these. Irrespectively of the mode of driving, the belt can along the helical path be subjected to relatively high tensile stress, which may result in the belt abutting hard against the outside of the drum. This in turn results in a considerable friction between the conveyor belt and the drum in respect of the moving of the conveyor belt both in the circumferential direction around the drum and axially along the drum, said friction contributing to an increase of the stress affecting the conveyor belt along the helical path.
Prior art solutions have coped with the circumferential friction only, usually by a positive engagement between the drum and the inside of the conveyor belt along the helical path.